MX2007008934A

MX2007008934A - Belt drive system.

Info

Publication number: MX2007008934A
Application number: MX2007008934A
Authority: MX
Inventors: Lacy Fraser; Richard Anthony Cherry; John W Black
Original assignee: Gates Corp
Priority date: 2005-01-10
Filing date: 2005-12-19
Publication date: 2007-09-14
Also published as: BRPI0519750A2; JP2008527264A; KR100940553B1; RU2355924C1; US20060154766A1; KR20070094642A; CA2592777A1; EP1836411A1; AU2005324423A1; WO2006076125A1; RU2007130553A; CN101099054A; JP4694574B2

Abstract

A belt drive system having a belt having a belt body. A tensile cord disposed in the belt body running along a longitudinal axis. A plurality of belt teeth disposed on an outer surface of the belt body, the belt teeth oriented transverse to the longitudinal axis. A belt land disposed between the belt teeth. A driver sprocket attached to an engine crankshaft, the engine having a plurality of cylinders. A driven sprocket. The number of grooves on the driver sprocket being an integer multiple of the number of engine cylinders divided by two. The number of grooves on the driven sprocket being an integer multiple of the number of grooves in the driver sprocket. The number of belt teeth, land length and sprocket groove spacing is dependent on the number of engine firing events per crankshaft revolution thereby reducing the frequency of the belt/pulley meshing to a level within the orders of engine frequencies.

Description

BAND TRANSMISSION SYSTEM The invention relates to a belt transmission system and more particularly to a belt drive system comprising a belt and a gear wheel in which the number of teeth, the length of the flat portion and the spacing of the grooves depends on the number of engine ignition events per revolution of the crankshaft whereby the frequency and noise are reduced by having the belt / pulley the same gear frequency as the engine start command.

Synchronous bands, or toothed bands, are used in power transmission systems when it is necessary to synchronize the driven components. The synchronization is achieved by the interaction of transverse teeth placed in the band with grooves in a driven and driven gear. The engagement of the teeth with the respective slots serves to mechanically coordinate the rotation of the sprockets and consequently the driven equipment.

The synchronous bands comprise a plurality of teeth mounted transversely in the band. The transmission of power occurs at the coupling point of each tooth with the gear in a plane substantially tangent to the gear at the coupling point. As a result, the teeth are mostly in drag.

Synchronous bands having a relatively greater flat area or spacing between the teeth are also known. These bands rely in part on the interaction of the friction of the flat part with the periphery of the gear to transmit the dynamic moment of force. The ability to transmit the dynamic moment of force is a function of Accumulated contact angle of the band around the sprocket, the installation tension and the coefficient of friction of the belt surface.

Representative of the trade is Patent No. 4,047,444 (1977) to Jeffrey which discloses a synchronous band and a gear wheel in which the transmission between the spaced teeth is mainly by frictional contact of a band at the peripheries of the teeth of the tooth. wheel.

Previously it was only relied on to have a differential spacing of the grooves between the driven and driven sprockets which was based in part on different web tensions. The problem of reducing operational harmonies and noise in previous applications was not addressed or solved.

What is needed is a belt drive system that provides a belt and a cooperating cogwheel in which the number of belt teeth, the length of the flat part and the spacing of the sprocket grooves depend on the number of events of ignition of the engine by revolution of the crankshaft whereby the frequency of the gear of the belt / pulley is reduced to a level that does not differ from the frequency orders of the engine. This invention satisfies this need.

The primary aspect of the invention is to provide a band and a co-operating cog in which the number of teeth of the band, the length of the flat part and the spacing of the grooves of the gear depend on the number of ignition events of the gear. engine by revolution of the crankshaft whereby the gear frequency of the belt / pulley is reduced to a level that does not differ from the motor frequency commands. Other aspects of the invention will be pointed out or they will be obvious through the following description of it and the accompanying drawings.

The invention comprises a band transmission system having a band and a body. A tension rope placed on the body of the band runs along a longitudinal axis. A plurality of teeth disposed on an outer surface of the body of the band, the teeth oriented transverse to the longitudinal axis. A flat part of the band is placed between the teeth. A drive sprocket coupled to the crankshaft of an engine, in engine with a plurality of cylinders. A cogwheel driven. The number of slots in the drive sprocket being a multiple of the number of cylinders of the motor divided by two. The number of slots in the driven sprocket being a multiple of the number of slots in the sprocket. The number of teeth of the band, the length of the flat part and the spacing of the slots of the sprocket depends on the number of ignition events of the engine per revolution of the crankshaft so that the frequency in the gear of the belt is reduced / pulley at a level within the motor frequency commands.

The accompanying drawings, which are included and are part of the description, illustrate the predominant incorporations of this invention and together with a description, serve to explain the principles thereof.

Fig. 1 is a schematic diagram of a previous system. Fig. 2 is a side view of a creative band and sprocket. Fig. 3 is a side view of a groove in the gear wheel.

Fig. 4 is a side view of a groove in the gear. Fig. 5 is a side view of a creative band. Fig. 6 is a side view of a creative band. Fig. 7 is a graph showing the angular vibration versus the installation voltage using the system of the invention. Fig. 8 is a graph showing the effective voltage versus the installation voltage using the system of the invention. Fig. 9 is a graph comparing the harmonies in order 19. Fig. 10 is a graph comparing the harmonies in order 8. Fig. 11 is a perspective view of a previous band showing the lengths of the teeth and the flat part. Fig. 12 is a perspective view of a creative strip showing the lengths of the teeth and the flat part. Fig. 13 is a perspective view of a creative strip showing the lengths of the teeth and the flat part. Fig. 14 is a partial perspective view of a sprocket for coupling the band in Fig. 13.

The systems of transmission by synchronous band are widely used in applications of automotive motors to drive e is of cams and other attachments, like pumps of gasoline, pumps of water, alternators, etc.

In some engines, the magnitude of the angular vibrations of one or more of the driven components requires the inclusion of a torsion damper attachment. The use of a shock absorber adds cost, complexity and weight to the engine.

This invention allows the elimination of these damping attachments, in some cases, increasing the rigidity of the transmission system through changes in the installation tension, increase in the coefficient and interaction of the interface of the teeth of the belt / pulley without detriment to the life of the band or increased noise in the system.

Increasing the tension of the system with conventionally toothed belts can result in an increase in the wear of the flat part of the belt due to higher contact pressures between it and the sprocket, as well as system noise increases due to a greater impact between the band / cogwheel.

This invention avoids the increased wear of the flat part of the band incorporating a considerable spacing between the teeth, defined as distance P, see Fig. 5, which reduces the pressure per unit area exerted by the tension forces in the flat part of the band. The creative configuration results in a distance P greater than normal, which in turn results in fewer teeth in the band that can give rise to the force load for a given length of a band. However, the creative configuration of the belt and the system compensate for this by optimizing the profile of the belt teeth and allowing the area of the flat part between the teeth to carry a significant proportion of the force load.

Furthermore, this invention avoids any increase in the noise associated with high web tensions by reducing the frequency of web vibrations and orders harmonics and allowing the frequency of engagement of the teeth of the band and the groove of the sprocket overlap on a frequency of synchronization of the ignition of the cylinder of the engine which considerably reduces the predetermined and undesirable orders of the harmonic vibration of the band . A considerable portion of the transmitted load is supported by the flat part of the band. Therefore, the transmission of power through the flat part of the band rests on the formula of Euler which describes the behavior of the band in what is transmitting the dynamic moment of force. In an operational condition, the band is under tension between a driven and driven cogwheel. The tension in a band entering a cogwheel (Ti) is different from the tension of the band when it comes out (T2). For a flat band using Euler's theory, the equation that relates the voltages Ti t T2 with the coefficient of friction (μ) and the contact angle of the band (?) In radians is: Ti = T μ? where e is the base of natural logarithms, 2.718, Ti is the voltage on the driver's side and T2 is the voltage on the driver's side. The impending slip is the upper limit of the power transmission capacity by friction of the belt.

This graph indicates the approximate limiting relationship for T? / T2 for a contact angle of the band of? = 180 ° as a function of the coefficient of friction between the flat part of the band and a cogwheel.

Assuming a Friction Coefficient = 0.35 With reference to the previous table, using this theory it is possible to transmit only by friction an effective voltage level (Te) of approximately 1500 newtons with T2 750N and a coefficient of friction (μ) of approximately 0.35. The effective voltage is defined as the difference between the voltage on the conductive side and the voltage on the conducted side of the band. The voltage of the conducted side is a function of the installation of the voltage (T? Nst). The voltage on the driver's side is a function of the load carried by the impulse (T).

If T? / T2 is less than or equal to eμ? the band will not slide off the cogwheel. For relationships greater than this, ie T? / T2 greater than e ?, a slip will occur.

However, in all cases the band will crawl on the cogwheels. Consider a piece of band of unit length moving in a first cog under tension Ti. Where this piece of band of unit length moves with the gear wheel the tension to which it is subjected decreases from Ti to T2 Due to its elasticity the piece of the band shrinks slightly. Therefore, the first cogwheel (motor) continuously receives a greater length of the band than it supplies and the speed of the surface of the gear is greater than that of the belt moving on it. Similarly, a second gear wheel (driven) receives a shorter length of the band than it supplies, and its velocity at the surface is less than that of the belt moving on it. This "crawling" of the band as it moves on the sprockets results in some inevitable loss of power that decreases efficiency.

In which the value of Ti is close to that of T2, that is to say (T? / T2 > l), the amount of drag will decrease because there is a minor change in the length of a unitary piece of belt moving on the sprocket. When Ti = T2, we obtain the condition "as installed" and the system can not transmit power.

The coefficient of friction for the flat part of the band is approximately 0.35 for the previous non-limiting examples. The range of sufficient friction coefficients (μ) for the flat part of the band (110) is from about 0.30 to about 0.40.

For a synchronous band drive, the previous theory of flat band is limited by the interaction of the teeth of the band with the grooves of the gear wheel. The transmission of power is achieved by sharing the load between the load of the teeth of the band and the effects of friction. In current practice, the majority of this load is supported by the teeth of the band.

The profile of the teeth is optimized dimensional and geometrically for the transport of the load and the gear of the band-gear wheel. For example, the profile of the teeth may be that disclosed in Patent No. 4,605,389 which is incorporated herein by reference. U.S. Patent 4,605,389 is cited as a profile example and is not intended to operate as a limitation on the types of profiles that can be used in this invention.

As noted, the creative band maximizes the length of the flat part thereof and therefore the contact area between the flat part of the band and the periphery of the gear while maintaining the attributes of a band synchrony toothed The system further provides non-interference between the tip of each tooth and the bottom or root of each co-operating slot of the gear to ensure that pressure is maintained in the area of contact between each flat part of the belt and the cooperating portion of the belt. surface of the cogwheel.

The ratio of the flat area to the area of the teeth for anterior bands having a standard pitch is approximately 0.50: 1, see Fig. 11. With reference to Fig. 5, Fig. 6 and Figs. 11-12, the area of the teeth is the flat area of the band occupied by the teeth, ie the length of the teeth () multiplied by the width of the band. The flat area is the area of the band occupied by the plane, that is, the length of the plane L multiplied by the width of the band. The width of the band is known in the trade and corresponds to broad industry standards. The creative band has a flat area relative to the area of the teeth in the range of approximately 1.5: 1.0 to approximately 10.0: 1.0, see the Fig. 12. In an alternate embodiment, with reference to Fig. 13, the relationship of the flat area to the area of the teeth is found in the range of about 0.20: 1.0 to about 0.09: 1.0. Consequently, this alternate incorporation describes a band where the die area is considerably larger than the flat area. In this case the power is transmitted through the friction between the lower part of the groove of the pulley 3002 and the upper part of the tooth 2010, see Fig. 14. Therefore, in this case, the depth of the teeth of the band is greater than the depth of the pulley groove and there is a gap between the upper part of the pulley tooth 3000 and the belt in the flat area 2011, to ensure contact between the surface 2012 and 3002 for the purposes of transportation of cargo. Fig. 14 is a partial perspective view of a sprocket for coupling the band in Fig. 13. The sprocket 3001 comprises the surface of the groove of the pulley 3002 which frictionally engages a surface of the upper part. of the tooth 2012. It is through this frictional coupling that the power is transmitted in this alternate embodiment. The third cog tooth 3000 couples the groove area of the 2011 band between the 2010 tooth to maintain synchronization. All other aspects of the construction of the band are revealed elsewhere in this specification for other additions.

Returning to the web construction, the materials further comprise a coating material used in a jacket layer 106 having a high coefficient of friction, see Fig. 5. The jacket layer may comprise textured or non-textured woven fabric. or textupsed or non-textuped nonwoven fabric containing aramid yarns, polyamide, PTFE, PBO, carbon polyester or other synthetic fiber or a combination of two or more of the foregoing. These can be applied as a continuous layer, they can be incorporated in the composite rubber material or they can be applied in the design of the tension piece.

The coating material of the jacket layer can be treated with a solvent based on polymeric or aqueous adhesives based on a resorcinol formalin latex system (RFL) containing any degree of HNBR, any degree of CR, sulfonated polyethylene or EPDM. These are used to maximize abrasion resistance, to maximize heat resistance and resistance to aging by thermal action and to ensure high levels of adhesion between this coating material and other band components at all temperature levels during the service life of the drive system. The overall result is a band that maximizes the capacity of the flat part of the band to carry a significant load level using the aforementioned flat band drive theory.

Again with reference to Fig. 5, the band further comprises tension pieces with high coefficient 107 arranged parallel to a longitudinal axis extending in an endless direction. The tension pieces may comprise twisted or twisted and folded yarns containing glass fiber, high strength glass, PBO, aramid, wire or carbon or combinations thereof. The tension rope can be applied as a single central part forming a helix across the width of the band, or apply in pairs of tension ropes with alternating twisted directions (z and s) forming a helix across the width of the band. The tension ropes can also be treated with solvent based on polymeric or aqueous adhesives based on RFL systems, including VPCSM / VPSBR / HNBR / CR in the RFL. They can contain any grade of HNBR, any grade of CR, sulfonated polyethylene or EPDM along with the dimension determination agent. These agents ensure high levels of adhesion between the piece of tension and other elastomeric components of the belt at all temperature levels during the service life of the drive system. They also minimize the degradation of the tensile force caused by fatigue to bending and abrasion between filaments, as the case may be, during the service life of the drive system. They also minimize the degradation of the tensile force caused by low temperature conditions in which they maximize the resistance to the fluids of the tension piece during the useful life of the band.

The web body 108 comprises an elastomeric composite with high coefficient based on any degree of HNBR, CR, EPDM, SBR and polyurethane or any combination of two or more of the above.

The body of the web may optionally include staple fibers for a fiber load, which may be used to increase the coefficient of the resulting compound. The type of fibers 40, 400, see Figs. 5, 6 which can be advantageously used as a reinforcement of the elastomer of the band includes meta-aramides, para-aramides, polyester, polyamide, cotton, rayon and glass, as well as combinations of two or more of the above, however it is preferable the para-aramid. The fibers can be fibrillated or pulped, a method well known in the art, when possible for a given type of fiber, to increase their surface area, or they can be crushed or in the form of a long fiber, as is also known in the office. For purposes of this disclosure, the terms "fibrillated" and "pulped" will be used interchangeably to indicate this known feature and the terms "shredded" or "chopped" will be used interchangeably to indicate the known distinguishing feature. a long from about 0.1 to about of 10 mm. The fibers may optionally be treated as desired based on the type of fiber to improve its adhesion to the elastomer. An example of a fiber treatment is any Resorcinol Latex Formaldehyde (RFL).

In a predominant incorporation where the fibers are of a cut or crushed variety, they can be formed of polyamide, rayon or glass, and have a relation between dimensions or "L / D" (ratio between the length of the fiber and the diameter) preferably equal to 10 or greater. In addition, the fibers preferably have a length from about 0.1 to about 5 mm.

In another predominant embodiment wherein the fibers are of a fibrillated or pulped-reduced variety, they are preferably formed from para-aramid and possess a specific surface area from about 1 m.sup.2 / g to about 15 m.sup. 2 / g., Preferably from about 3 m.sup.2 / g to about 12 m.sup.2 / g, and more preferably from about 6m.sup.2 / g to about 8 m.sup.2 / g and / or an average length from about 0.1 mm to about 5.0 mm, preferably from about 0.3 m to about 3.5 mm, and more preferably from about 0.5 mm to about 2.0 mm.

The amount of fibrillated para-aramid fiber used in a predominant embodiment of the invention can advantageously be from about 0.5 to about 20 parts per hundred weight of nitrile rubber; preferably from about 0.9 to about 10.0 parts per hundred weight of nitrile rubber, more preferably from about 1.0 to about 5.0 parts per hundred weight of nitro rubber and optimally from about 2.0 to about 4.0 parts by one hundred weight of nitplus rubber. The person skilled in the relevant art would recognize that at higher concentrations of fiber load, the elastomer preferably would be modified to include additional materials, e.g. plasticizers, to avoid excessive hardness of the cured elastomer.

The fibers can be dispersed randomly through the elastomeric material in the power transmission band or can be oriented in any desired direction. It is also possible and it is preferable for the toothed belts manufactured in accordance with this invention, that the fibers be oriented through the elastomeric material in the power transmission band, as illustrated for example in Fig. 13.

The fibers 40, 400 on the teeth 104, 105, 201 are preferably oriented longitudinally, in the direction of the path of the band. However, the fibers 40, 400 in the teeth 104, 105, 201 are not all parallel to the tension ropes 107, 203; the fibers 40, 400 in the teeth are positioned longitudinally, although they follow the flow direction of the elastomeric material during the formation of the teeth when they are formed according to the method of series construction. This results in the fibers 40, 400 being oriented on the teeth of the band 104, 105, 201 in a longitudinal, generally sinusoidal pattern, which coincides with the profile of the teeth.

When oriented in this predominant configuration, in which the direction of the fibers is generally in the direction of travel of the toothed belt, it has been found that the fibers 40, 400 located in the section of the rear surface of the band 120, 12000 inhibit the propagation of cracks in said surface, particularly the caused by operation at an excessively high temperature or ba, which otherwise generally propagates in a direction perpendicular to the direction of the path of the band. However, it should be understood that the fibers 40, 400 do not need to be oriented or can be oriented in a direction or directions different from those illustrated.

The application of the design principles described is described in the following example.

With reference to Fig. 1, a prior system has the following specifications: A toothed belt (B) has 135 teeth and 9,525 mm pitch (P). The drive length is 1285,875 mm. The sprockets are the following: - CRANK CRANKSHAFT CRANKSHAFT - CRANKSHAFT - 18 WAYS (W_P) - E-gearwheel is cam with 38 slots (CM1, CM2) - 4 cylinder engine The sprockets of the cam shafts (CM1, CM2) have a diameter of 113.84 mm. TEN and IDR denote a tensioner and a guide pulley respectively, each known in the art.

Again with reference to Fig. 1, the creative band and system replace the previous system is designed so that the length of the drive remains the same and the diameters of the sprockets are not exceeded.

The creative system incorporates a step (P) that depends in part on the overall length of the band drive. The number of slots in the crankshaft gear depends on the number of engine ignition events in one revolution of the crankshaft. The relationship between the width of the stiffness area of the strip and the length of the flat area depends on the pitch (P).

The band of the invention (B) has an integer number of teeth arranged transverse to the longitudinal axis, in this case 57 teeth, in contrast to the 135 teeth of anterior bands. In this example the step (P) of the band is 22.62 mm compared to 9.525 mm for the previous system. The crankshaft sprocket (CRK) (drive sprocket) has an integer number of slots which is a multiple of the number of cylinders of the engine divided by two, in this case 8 slots are selected (4 motor cylinders x 2). The camshaft gears (CM1, CM2) each have 2 times the number of slots in the crankshaft sprocket (8 slots), which in this case results in 16 slots in each sprocket. Of cam. The number of slots in the water pump gearwheel (_P) is also a whole number, in this case 8 slots. If necessary, for different strip constructions the pitch (P) can be adjusted to give a desired position of the tensioner arm.

For improved noise performance, the number of slots in the crankshaft sprocket is a multiple of the number of cylinders of the engine divided by two. This relates the number of slots in the crankshaft to the number of ignition events of the engine cylinder per revolution of the crankshaft. In this way, the frequency of engagement of the band / sprocket is considerably reduced and consequently the meshing noise makes it distinctive from other engine frequency command noise.

Although the previous example of a four-cylinder engine has 8 slots in the crankshaft sprocket, it also it can comprise any multiple of the number of cylinders divided by two, for example, 4 or 12 slots.

In operation, each tooth of the belt engages a groove of the drive sprocket and a groove of the driven sprocket in series to maintain proper synchronization of the driven accessories. The system requires at least two teeth of the belt to engage with the grooves of the drive sprocket and that two teeth engage with the grooves of the driven sprocket at all times to maintain proper timing. The number of teeth and, more particularly, the pitch, is directly related to the contact angle (a). That is, as the contact angle decreases the spacing of the tooth of the band and the spacing of the groove of the gear must decrease to ensure that at least two teeth of the band are in contact with the corresponding grooves of the wheel jagged at all times. In the limit the pitch of the tooth (P) is: P < (p / 180 °) * (r) * '(a) Where r = the diameter radius of the smallest sprocket step a = the contact angle of the band around the smallest sprocket.

Turning now to Fig. 2 which is a side view of a gear wheel and band of the invention, the marked position (A) represents the point of tangency of the passage of the conductor side in the flat part of the band with maximum load. Position (A) is where the band engages with the drive sprocket. The Band B coupled with the drive sprocket 1000 is shown being driven in the direction described by the arrow. The power, that is, the dynamic moment of force, transmits to the pulley driven by frictional contact between the flat surface of the belt and the periphery of the pulley.

The crankshaft gear 100 comprises 8 grooves for coupling the belt. Point (A) represents the band-gearwheel position when a cylinder ignition event occurs. With respect to the position (A), at least about 50% between the point (A) where the band engages the driving sprocket and the first immediately coupled tooth of the band (A ') at least 50% of the part Flat of the band is in contact with the cogwheel in each event of ignition of a cylinder. The synchronization can be adjusted in such a way that point (A) results up to 100% of the flat area between point (A) and the first tooth immediately coupled (A ') on the conductive side of the band that is being coupled at the moment of each cylinder ignition event.

This synchronization method minimizes the load of the tangential deflection stress of the tooth caused by each ignition event of the engine, that is, a maximum portion of the flat part is engaged with the sprocket during an ignition event of the engine to maximize the contribution by friction with the capacity of the tangential deflection stress of the tooth during the transmission of power. Therefore, the gear of the teeth is mainly used to ensure proper synchronization. The power or dynamic moment of force is transmitted mainly by coupling the flat part of the belt with the cooperating surface in the gear wheel.

Fig. 3 is a profile of a slot of the gear wheel. Each slot 1000 in turn comprises a first 101 and a second slot 102. Slot 1000 meshes with the cooperating profile of the band described in FIG. 5, ie, teeth 104, 105 engage cooperatively with slots 101, 102, respectively. The planar areas 300, 301 couple the flat area of the band 110. Fig. 4 is a profile of a slot of a sprocket. In this example, the slot 2000 comprises a single slot 200. The slot 200 meshes with a tooth of the band 201 as shown in FIG. 6. The flat portions 500, 501 engage the flat portions of the band 205. .

Fig. 5 is a cross-sectional view of a band. The band comprises the portions of the teeth 104 and 105 placed in the body of a band 108. A concavity or slot 109 is positioned between the portions 104 and 105. The portions 104 and 105 in combination with the concavity 109 comprise a single tooth T for the purposes of this revelation. The tooth T has a long W. Between each tooth T is placed a flat area 110 having a length L. In the band of the invention the flat area 110 has a length L greater than the width of the length of the tooth. Step P is the space between the corresponding points of consecutive teeth. Optionally, the concavity 109 can be omitted from the shape of the tooth, see Fig. 6, with the co-operating tooth 103 likewise omitted from the cogwheel.

The tension rope 107 is positioned along a longitudinal axis of the band. The longitudinal axis runs in an endless direction. The jacket layer 106 is placed on a coupling surface of the sprocket with the band.

Fig. 6 is a cross-sectional view of a band. The band comprises the teeth 201 placed on the body of a band 204. A tension string 204 is positioned along a longitudinal axis of the band. The longitudinal axis runs in a endless direction. The jacket layer 202 is placed on a coupling surface of the sprocket with the band. The tooth 201 has a length W. Between each tooth 201 is a flat area 205 with a length L. In the band of the invention the flat area 205 has a length L equal to or greater than the length of the tooth W.

The creative system provides several improvements over previous systems. Fig. 7 is a graph describing the reduction of angular vibration (AV) of a cam shaft of an engine as a function of the installation voltage of the belt without the need for a cam damping mechanism. One may note that by using the band and the sprocket of the invention, the vibration is considerably reduced from 2.2 ° to 0.9 °. It is preferable that the angular vibration in a system be less than 1.5 ° to minimize the wear of the band and the system. Accordingly, the invention allows a reduction in the complexity of the system and in the cost through the omission of cam dampers.

The amplitude of the vibration of the passage of the conduction side of the band during its operation is reduced by approximately 30% using the band of the invention. The speed at which a resonance occurs in the passage of the conduction side of the band increases approximately from 2000 RPM to 3000 RPM.

With reference to Fig. 8, the effective voltage (Te) is reduced by increasing the installation voltage (T? Nst) of 230N in applications prior to 375N for the creative system. In previous systems this increase in voltage would result in a reduction in the service life and an increase in noise. This is not the case for the creative system according to the reasons mentioned before.

With respect to the noise generated by the system, this creative system considerably reduces the order 19 and the related harmonic frequencies, see Fig. 9, which are associated with the distinctive noise caused by the gear / sprocket gear in the previous systems . The additional order 8 and related harmonic frequencies, see Fig. 10, are entered but these occur at the same frequency as other motor commands such as the firing order. In each of Fig. 9 and Fig. 9, the creative system is installed with an effective voltage of 375 Newtons without a damper. On the other hand, the other systems include a shock absorber, which represents an additional cost. The creative system reduces the frequency of vibrations caused by the belt / pulley gear to a level indistinguishable from the motor's frequency commands.

Although forms of the invention have been described herein, it will be obvious to those skilled in the art that variations may be made in the construction and relationship of parts without departing from the principle and scope of the invention described herein.

Claims

Claims:

A band transmission system comprising: a band with a body; a tension rope placed on the body of the band running along a longitudinal axis; a plurality of teeth positioned on an outer surface of the belt body, a flat part positioned adjacent the teeth of the belt; a drive sprocket coupled to the crankshaft of a motor; a driven gear wheel; the number of slots in the drive sprocket being a multiple number of the number of cylinders of the motor divided by two; and between a point (A) where the band engages with the driving sprocket and the first immediately coupled tooth (A ') at least 50% of the flat part of the band is in contact with the sprocket in an ignition event of a cylinder.
The system as in claim 1, wherein the space of the teeth of the band is such that at least two teeth are coupled with two slots in the sprocket having the smallest contact angle.
The system as in claim 1, wherein a multiplier for the number of slots in the driven sprocket compared to the sprocket is an integer equal to or greater than two.
The system as in claim 1, wherein the passage of the teeth of the band is determined by the formula P = (n / 180 °) * (r) * (a) where r = the diameter radius of the smaller sprocket pitch; and a = the contact angle of the band around the smallest sprocket.
5. The web transmission system as in claim 1, wherein the web further comprises a load of fibers.
6. The belt drive system as in claim 1, wherein the number of grooves in the driven gear is a multiple of the number of grooves in the drive gear.
7. A band comprising: an elastomeric body; a tension piece placed in the body parallel to a longitudinal e; a plurality of teeth placed on the body in a direction transverse to the longitudinal axis, each tooth with an area; a flat portion placed between the teeth, the flat portion with a flat area; the flat area being greater than the area of the teeth, where the relation between the flat area and the area of the teeth is in the range of approximately 1.50: 1.0 to 10.0: 1.0; and the planar portion with a coefficient of friction for transmitting a dynamic force moment by coupling with a surface of a sprocket.
8. The band as in claim 7, wherein the coefficient of friction is in the range of about 0.30 to about 0.40.
. The band as in claim 7 furthermore comprises a load of fibers.
0. A band transmission system for an internal combustion engine comprising: a drive wheel and a driven wheel; a band coupled between the driving gear and the driven gear; the band comprising a body, transverse teeth having a passage, a tension cord embedded in the body disposed in an endless direction and a flat part with a flat area positioned between the adjacent teeth; the driving sprocket with a predetermined number of cooperating grooves corresponding to a multiple of the number of cylinders of the engine divided by two; wherein the ignition timing of the engine cylinders determines the amount of flat part of the belt in contact with the driving sprocket on the driven side of the belt with respect to a point (A) during an ignition turnout of the cylinders of the engine to minimize the loading of the teeth of the belt, and a point (A) where the belt engages the driving sprocket and the first tooth of the belt immediately coupled (A ') at least 50% of the part Flat of the band is in contact with the gear in an event of ignition of a cylinder.
11. A band transmission system comprising, a band with a body; a tension rope placed on the body that runs along a longitudinal e; a plurality of teeth placed on an outer surface of the band body, a flat part placed between the adjacent teeth of the band; a drive sprocket attached to the crankshaft of a motor; a driven gear wheel; the number of slots in the drive sprocket that is a multiple of the number of cylinders of the engine divided by two; the number of slots in the driven sprocket that is a multiple of the number of slots in the sprocket; and the frequency of engagement of the teeth of the band with the grooves of the drive sprocket is not substantially distinguishable when it is superimposed on the ignition timing frequency of a cylinder of a motor.
12. The band transmission system as in claim 11, wherein: the ignition timing of a motor cylinder determines the amount of flat part of the band in contact with the drive sprocket on the conductive side of the band with respect to a point (A) during an ignition event of an engine cylinder to minimize the loading of the belt teeth; and between the point (A) where the band engages with the driving sprocket and the first immediately coupled tooth (A ') at least 50% of the flat part of the band is in contact with the sprocket in an ignition event of a cylinder.
13. The band transmission system as in claim 12, wherein the relationship between the flat part of the band and the tooth area is in the range of about 1.5: 1.0 to about 10.0: 1.0. The web transmission system as in claim 11, wherein the web body further comprises a load of fibers. The band transmission system as in claim 11, wherein the relationship between the planar area and the tooth area is in the range of about 0.20: 1.0 to about 0.09: 1.0. The web transmission system as in claim 15, wherein a load is transmitted by frictional engagement between the upper surface of the teeth and the groove surface of the pulley. A band comprising: an elastomeric body; a tension piece placed in the body parallel to a longitudinal axis; a plurality of teeth placed on the body in a direction transverse to the longitudinal axis, each tooth with an area; a flat portion placed between the teeth, this flat portion with a flat area; the flat area being smaller than the area of the teeth where the relationship between the flat area and the area of the teeth is in the range of about 0.20: 1.0 to about 0.09: 1.0; and the area of the teeth with a coefficient of friction to transmit a dynamic moment of force by coupling with the surface of a gear wheel.